Oil and gas flow systems are required in the production of hydrocarbons. It is necessary to flow produced oil substantial distances from the point of production in a subterranean formation of a reservoir through production tubing to the top of a producing well. Once oil is produced from a well, it is sometimes necessary to move the oil a substantial distance through pipes or pipelines. Hydrocarbons, such as oil and gas, are produced with water in many instances. Thus, it is common to move oil and water together in a multiphase flow stream.
It is desirable to improve the flow performance of oil/water mixtures in pipes. The improvement in flow performance may reduce the energy lost in transporting such mixtures, enabling greater production from wellbores in some instances. In the case of pipelines, reducing the energy lost in transporting multiphase fluids through a pipeline is desirable.
Many surface modification techniques that are known for the interior of pipes are designed for the flow of a single phase of fluid through the pipe. This could be a single phase of water, or a single phase of a hydrocarbon, or another compound. However, the application of a surface modification technique that is designed for enabling reduced friction of flowing fluid of a single phase fluid does not address the problem of multiphase fluid flow. A surface modification technique that enables reduced friction for the flow of water is not likely to be as effective for the flow of a water/oil mixture. Likewise, a surface modification technique that enables the reduced friction flow of oil only also is not likely to be effective for the flow of an oil/water mixture.
In the production of hydrocarbons from subterranean wells, it is common for the early life of a well to produce substantially all hydrocarbons. However, later in the life of a well, a substantial amount of water is produced with the oil. Near the end of the life of a producing hydrocarbon well, the amount of water continues to increase, in many cases, to a point at which most of the produced fluid is water and the minority of the produced fluid is hydrocarbons. Thus, a strategy for reducing frictional flow of fluids from a well must take into account that the pipes or tubing installed as production tubing in a wellbore during well construction will encounter different proportions of oil to water during the production life of the well. The amount of water typically increases substantially during the producing life of the well. Further, it is likely to be uneconomical to replace production tubing during the life of a well. Therefore a need exists to provide a production tubing that is adapted to reduce the frictional flow of a multiphase flow that may be mostly hydrocarbons during the early life of the well and mostly water during the later life of the well.
It is generally desirable to reduce the kinetic energy lost in transporting multiphase oil/water mixtures in pipes and tubulars. The invention is directed to reducing frictional pressures in the transfer of oil/water mixtures in pipes, thereby conserving energy or maximizing production from a subterranean well.